void hello() {
  print(hello);
}

abstract class Greetings {
  void hello();
}

class English extends Greetings {
  @override
  void hello() {
    print('Nice to meet you!');
  }
}

class Chinese extends Greetings {
  @override
  void hello() {
    print('你好');
  }
}

showAlert(Function() function) {
  function.call();
}
